Antitheft device for an automobile

ABSTRACT

Automobiles such as a cash carrying car, truck, police car and so on, are prevented from being ridden away during loading or unloading cash or goods or being robbed by robbers after having been forcibly stopped on road. When a door of the automobile is opened, a opened-door detection switch operates and a first-control means stores in its memory the switch&#39;s action and cuts off an engine start-up circuit. The engine can be restarted when a registered password is entered into the device through a password inputting means, whereby a second-control means stores the signal and enters a resetting signal into the first control means to restore the engine start-up circuit. At the same time, a resetting signal produced by a reset signal generating means is inputted into the second control means which is thereby restored to the initial state.

BACKGROUND OF THE INVENTION

The present invention relates to an antitheft device for use in any kindof automobile such as a cash carrying car, a truck, a police car and soon, and more particularly to a system for preventing a car or a truckfrom being ridden away during loading or unloading cash or goods or forpreventing the car or the truck from being robbed by robbers after ithaving been forcibly stopped on road.

There have been frequent robberies of cash carrying cars and the likeand various systems have been also proposed as a countermeasure, forexample, to strictly hold a key or to make it impossible to start theautomobile by key without preliminary inputting a correct passwordspecified for said automobile.

The above-mentioned countermeasure for inputting the specified passwordhas such a drawback that it is helpless against the robbers' attack ifthe car engine has been started.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a antitheft devicefor an automobile, which prevents the automobile from being ridden awayby making its engine start-up circuit inoperative when the door isopened, thus being free from the above-mentioned drawback of the priorart.

BRIEF DESCRIPTION OF THE DRAWINGS

The side FIGURE is a circuit diagram for showing an embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An antitheft device for an automobile according to the present inventionincludes a plurality of opened-door detection switches for detecting theautomobile's door in opened state, a first-control means for storing theoperation of the detecting switch in its memory until a resetting signalis inputted and for retaining an engine start-up circuit in cut-offstate for the period of keeping a memory of the detecting switch'soperation, a password inputting means for inputting a registered signal,a second-control means for acting at the time of inputting theregistered signal, for keeping the action until the resetting signalhaving been inputted and for inputting a resetting signal into the firstcontrol means for the period of keeping a memory of its own actingstate, a reset signal generating means for restoring the second controlmeans into its initial state by inputting a resetting signal into thesecond control means.

The antitheft device for preventing an automobile from being riddenaway, according to the present invention, can operate as follows: When adoor of the automobile is opened, a opened-door detection switchoperates and a first-control means stores in its memory said switch'saction and cuts off an engine start-up circuit thereby making itimpossible to start up the engine by turning the key.

Restarting the engine becomes possible when a registered password isentered into the device through a password inputting means, thereby asecond-control means stores said signal and enters a resetting signalinto the first control means to restore the engine start-up circuit. Atthe same time, a resetting signal produced by a reset signal generatingmeans is inputted into the second control means which is therebyrestored into the initial state.

Consequently, when any door is opened again, the device can operate tocut off the engine start-up circuit and to maintain said circuitinoperative as far as the password is not inputted.

The FIGURE is a circuit diagram showing an embodiment of the presentinvention. In the drawing, there are shown two opened-door detectionswitches 1, each of which serves for one of the automobile's doors andis set in OFF state, as in FIGURE, when the door is shut, and becomes ONwhen the door is opened. Microswitches, reed switches and other switchesmay be also used for the above-mentioned purpose. Especially, it is veryconvenient to use reed switches since they may be mounted at door frameside by mounting corresponding permanent magnets for them at door side.It is also convenient to set each opened-door detection switch 1 so thatit may be closed when the door was opened to the extent allowing thehuman body to pass therethrough. Frequent operation of the system with aminute opening of the door may be thus avoided. An opened-bonnetdetection switch 2 turns ON when the bonnet (i.e. hood) opened and itturns OFF when the bonnet is shut.

A first-control means 3 includes two inverters INV1 and INV2, aflip-flop FF1 and a relay RY1 with its contact ry1. When the opened-doordetection switch 1 closes, the first control means operates to open theengine start-up circuit by breaking the relay contact ry1. A passwordinputting means 4 may be a keyboard, magnet card, IC card, electronickeys or other means being capable of inputting a password predeterminedfor the automobile to be protected. 5 is a password memory (storage) 5wherein the password for the automobile is stored, and 6 is a matchingmeans whereby the password inputted by the password inputting means 4 ischecked for correspondence with the password stored in the passwordmemory 5 and an identifying signal is generated.

A second control means 7 comprising a flip-flop FF2 which receives theidentifying signal from the matching means and changes its output toreset the first control means 3. An alarm means 8 including invertersINV3, INV4 and INV5, a NOR gate NOR1 and relay RY2 with its contact ry2can generate a loud warning signal by closing a horn circuit at the timeof opening the door and/or the bonnet. A reset signal generating circuit9 which includes NOR gates NOR2 and NOR3, a delay circuit composed of acondenser Co and a resistor Ro, inverters INV6 and INV7 can generate aresetting signal to return the second control means to the initial stateafter a fixed time of delay. The FIGURE, a resistor and a diode aredenoted by characters R and D respectively.

Operation of the device is explained as follows: A) the case of openingthe automobile's door

When the door is opened, the opened-door detection switch 1 turns ON tocause inverter INV1 produce a signal "High" whereby the flip-flop FF1reverses its output and produces the signal "High" at its terminal "Q"and, therefore, the output of the inverter INV2 becomes "low" toenergize the relay RY1 to open its contact ry1. Consequently, the enginestart-up circuit is opened and the engine can not be started as long asthe flip-flop is not reset. When the door is closed again and theopened-door detection switch 1 is turned OFF, the output of the inverterINV1 is maintained at "Low" level and the flip-flop FF1 remains as itis. The engine start-up circuit is still in OFF state.

(B) In case the bonnet is opened in the state (A)

When the bonnet is opened, the opened-bonnet detection switch 2 closesto cause the inverter INV4 to generate a signal "Low". Since in thestate (A) the flip-flop FF1 has the "Low" level signal at its terminalQ, the output of the NOR gate NOR1 is turned to "High" and the output ofthe inverter INV5 becomes "Low", resulting in that the relay RY2 isenergized to close its contact ry2 to turn ON the horn circuit, that is,the horn sounds to inform of the bonnet being opened.

(C) In case the engine is started by closing the door from the state (A)

The engine start-up circuit is kept in OFF state under the action of thefirst control means since the door was once opened. To restore saidcircuit to its initial state, the password is entered into the device bymeans of the password inputting means 4. The matching means 6 makes acheck of the entered password by referring to the password stored in thepassword memory 5 and generates an identifying signal if the enteredpassword has been proved to be correct. At the same time, the flip-flopFF2 changes its output inversely to produce at its terminal "Q" a signalof "High" level, namely, a resetting signal for returning the FF1 in theinitial state. Consequently, relay RY1 is restored to make its contactry1 closed for switching ON the engine start-up circuit. The engine isnow operable.

On the other hand, the flip-flop FF1 is restored to have the output of"High" level at its terminal "Q" and the NOR gate NOR1 has the output of"Low" level. The flip-flop FF2 changes output level at its terminal "Q"from "High" to "Low" with discharging the accumulated electric chargefrom the condenser Co through the resistor Ro so as to delay the outputof a "Low" level signal at the inverter INV7 for a certain period (forexample, of 60 sec.). The NOR gate NOR3 thereby generates the outputsignal to reset the flip-flop FF2. The flip-flop circuit FF2 is thusautomatically restored into the initial state.

The purpose of the above-mentioned delay operation is as follows:

When the flip-flop FF1 has the "Low" level signal at its terminal "Q",that is, before resetting the flip-flop FF2, the opened-bonnet detectionswitch 2 turns ON, the inverter INV4 changes its output to "Low" leveland therefore the NOR gate NOR1 has the "High" level output, resultingthat the relay RY2 operates to the switch ON the horn circuit. On thecontrary, as far as the resetting signal from the flip-flop FF2 isapplied to the flip-flop FF1, the flip-flop FF2 may have the "High"level signal at its terminal "Q" irrespective of whether the output ofthe inverter INV is "High" or "Low" and therefore the relay RY2 can notbe energized. Namely, if the bonnet is once opened during the delay timedetermined by the delay circuit composed of the condenser Co and theresister Ro, the horn will not sound as the bonnet being in openedstate.

Although in the above-mentioned embodiment a password is adopted forrestarting the engine of the automobile, it is also possible to use anytype of signal if it is registered in advance. It is allowed to specifythe ON/OFF operations of the switches 1 and 2 in reverse to theabove-described embodiment if an additional inverter is provided in thecircuit.

Furthermore, it is also possible to use a plurality of passwords, forexample, three kinds of passwords A, B and C which are stored in thememory 5 in such a way that they may become effective one by one in saidorder. In this case the driver is firstly informed of only one passwordA and drives the automobile to the first designated place. When theautomobile was stopped and its door was opened, the password A becomesinoperative and the password B becomes effective to use. Therefor, thedriver is informed of the second password B necessary for restarting theautomobile's engine by radiotelephone from the control center. The thirdpassword C shall be used after the second password B comes out of use.Such a combination of passwords provides a complete protection againstrobbery.

If the driver stopped the automobile at a place where the instruction byradiotelephony from the control center can not be received, he mustbring the automobile to a spot where the radio communication with thecontrol center is possible. In view of the above-mentioned case, such aprovision is also made that the automobile's engine may be driven onlyfor a short time (for example, 30 seconds) by using the engine key or byputting an optional number into the antitheft device. Namely, the drivermay drive the automobile to the necessary position by repeating theabove-mentioned operation.

As is apparent from the foregoing description, since the antitheftdevice according to the present invention comprises a plurality ofopened-door detection switches for detecting corresponding doors inopened state, a first-control means for storing the operation of saiddetecting switch in its memory till a resetting signal has been inputtedand for keeping an engine start-up circuit in cut-off state for theperiod of storing the detecting switch's operating state, a passwordinputting means for entering a registered signal, a second-control meansfor making action at the time of inputting the registered signal and forkeeping the action until the resetting signal having been inputted andfor inputting a resetting signal into the first control means for theperiod of storing its own acting state, a reset signal generating meansfor restoring the second control means in its initial state by inputtinga resetting signal into the second control means, the device is capableof cutting off the engine start-up circuit by the action of the firstcontrol means when the door is once opened, and of maintaining saidcircuit in OFF condition as far as the first control means is notrestored by inputting the registered password. Accordingly, it iscompletely avoided that the automobile is ridden away if the driver getsout of said automobile with the key left therein. The great advantage ofthe device is to provide a complete antitheft means of the automobilesuch as a cash carrying car, truck, police car and so on.

I claim:
 1. An antitheft device for an automobile, comprising;aplurality of opened-door detection switches for detecting the opening ofdoor of the automobile; an engine start up circuit connected to inhibitthe starting of the engine of the automobile in a cut-off state of thestart up circuit; a first-control means comprising a memory for storingthe operation (ON state) of any of said detecting switches and holdingsaid engine start up circuit in said cut-off state until a resettingsignal has been inputted thereto; a password inputting means forgenerating an identifying signal in response to the input of a passwordthereto; a second-control means connected to be responsive to thegeneration of said identifying signal for generating a resetting signaland for applying the resetting signal to the first control means forthereby removing said engine start up circuit from said cut-off state;and a reset signal generating means connected to be responsive to thegeneration of said resetting signal for controlling said second controlmeans to stop the generation of said resetting signal.
 2. An antitheftdevice for an automobile according to claim 1, further comprising awarning means and an opened-bonnet detection switch connected to actuatesaid warning means when said open-bonnet detection switch and theopened-door detection switch are operated.
 3. An antitheft device for anautomobile according to claim 1, wherein said reset signal generatingmeans comprises means for resetting the second control means with acertain delay time after activation of the second control means by saididentifying signal.
 4. An antitheft device for an automobile accordingto claim 1, wherein the password inputting means comprises a keyboard ora magnetic card or an IC card or an electronic key.
 5. An antitheftdevice for an automobile according to claim 1, wherein the opened-doordetection switch consists of a reed switch installed on the door frameof said automobile and a permanent magnet installed on the door of saidautomobile.
 6. An antitheft device for an automobile according to claim1, wherein the opened-door detection switch is mounted to be actuatedwhen the door of said automobile is opened to such a degree that aperson may pass therethrough.
 7. An antitheft device for an automobileaccording to claim 1, wherein said password inputting means comprises apassword memory and a matching means connected to compare a passwordinputted through the password inputting means with a password stored inthe password memory and, when both passwords are matched with eachother, to generate said identifying signal.
 8. An antitheft device foran automobile according to claim 7, wherein said password memory has aplurality of passwords stored therein adapted to be sequentiallycompared with input passwords in a given order.
 9. An antitheft devicefor an automobile according to claim 8, comprising means for giving theidentification of a password to be used to a driver of the automobile byradio-communication from a control center.